This invention relates generally to surgical devices and more particularly, to an improved balloon catheter apparatus and method for enlarging a flow path within a vascular conduit or other body passageway.
Catheters having inflatable balloons affixed to their leading edge are commonly used in a variety of surgical applications. One application for such a xe2x80x9cballoon catheter,xe2x80x9d is for dilating blood vessels which have been partially or entirely blocked by deposits or other obstructions. The balloon catheter is introduced into the affected blood vessel and the deflated balloon is maneuvered into a blocked or otherwise obstructed flow path within the vessel. By inflating the balloon, the deposits or obstructions are compressed against the inner wall of the vessel, thereby enlarging the flow path. Other applications include the removal and/or compression of adherent materials such as atherosclerotic plaque, thrombosis, stenosis, occlusions, clots, stones, and other potentially obstructive material from within vascular conduits and other body passageways.
Prior devices used in such applications include catheters having a catheter shaft and an inflatable balloon located near the leading or distal end of the catheter. The balloon of such a catheter usually consists of an inflatable sleeve or bulb fitted on the outside of the tubular catheter shaft. The balloon is inflated by the infusion of a fluid into the balloon chamber from within the shaft. It is important that the balloon""s inflation be controlled, such that it is not overinflated, resulting in an overexpanded balloon which can rupture or otherwise damage the affected vascular conduit or other body conduit.
In an effort to reduce the dangers of over expansion and thus, potential damage to the conduit, modem catheters are commonly configured with reinforced balloons that can only expand to a predetermined maximum diameter, regardless of the interior pressure applied. While effective at limiting the radial expansion of the associated balloon, these catheters are only effective when used within a vascular or other conduit of a specified size. Conduits having different or changing diameters may require the use of a number of such catheters, each having a specified maximum balloon diameter. In addition, many applications could benefit from a balloon having a specific configuration or shape for use within the conduit. These specific shapes or configurations could advantageously be used to compress or remove occluding material, for infusing treatment fluids as well as for therapeutic effects. Thus, there is a need for a balloon catheter which can restrain the maximum radial expansion of the inflated balloon and can also configure the inflated balloon to a specified shape or configuration. There is also a need for such a balloon catheter which has the ability to limit the radial expansion of the inflated balloon to a number of different maximum radial diameters.
When removing occluding material from within a vascular conduit, such as a blood vessel, it is important that the surface of the balloon catheter be relatively smooth in order to prevent damage to the inner lining. Prior art balloon catheters are generally provided with a smooth outer surface for this purpose. However, it is often desirable to have an abrasive outer surface for contacting the inner walls of the vascular conduit. The abrasive outer surface allows for improved removal of the occluding material as well as for traction. In addition, there is also a need for a balloon catheter having a more abrasive outer surface for use in other applications such as the removal of thrombus or other obstructions from within an artificial graft. These applications often require more intense scrubbing. Thus, there is a need for a balloon catheter which has an abrasive outer surface, yet which is not damaging to the inner lining of the vascular conduit or other conduit. There is also a need for such an abrasive outer surface that retains a consistent abrasiveness regardless of the balloon""s inflation or expansion. There is also a need for a balloon catheter which includes an abrasive outer surface suitable for removing thrombus or other occluding material from within an artificial graft.
The present invention overcomes these problems of the past by providing a surgical device having a coaxial over-structure or outer sleeve which is operable independently of an internally disposed balloon or bladder. By using an outer sleeve, which is independent of the generally surrounded balloon, and which is radially expandable and collapsible through actuation of the surgical device, the maximum radial and axial expansion of the inflated balloon can be controlled. In addition, the use of an outer sleeve which is independently expandable into a number of predetermined configurations, allows the balloon to be constrained within a plurality of different sizes and shapes. The surgical device of the present invention is thus, capable of conforming to a plurality of different body conduits and sizes without the need to change to a different size surgical device. The surgical device of the present invention also solves the need for a device which can control the size and shape of an internal balloon or bladder regardless of the application.
The present invention also satisfies the need for a surgical device which provides traction within a vascular conduit or other passageway by providing a balloon catheter having an independent outer sleeve. The outer sleeve is preferably configured with an abrasive or tractive outer surface for contact against the inner walls of the conduit. The outer sleeve is advantageously made from a woven mesh material which can be expanded and collapsed into a number of predetermined shapes and sizes. The balloon may be inflated to conform to the outer sleeve and may be constrained within the predetermined configuration of the mesh sleeve. Fluid pressure may be increased within the balloon to increase traction with the wall of the conduit. In addition, the mesh sleeve may also be utilized to limit the overall length of the inflated balloon.
The present invention also satisfies the need for a surgical device which may be used for cleaning and removing obstructions and clots from within an artificial graft by providing a balloon catheter having an independent mesh sleeve with an abrasive outer surface. For purposes of this disclosure, an artificial graft or shunt is considered a vascular conduit and all discussions relating to vascular or other body conduits shall include artificial grafts, shunts and similar passageways.
By providing a balloon catheter which utilizes procedures similar to those of the prior art balloon embolectomy catheters, a surgeon can effectively use the balloon catheter of the present invention without the need to learn new or additional procedures. The balloon catheter of the present invention includes an outer mesh sleeve made from a woven filament which is connected to the catheter at one end, either proximally or distally of the balloon, and which has an irregular outer surface. Inflation of the balloon expands the outer mesh sleeve and compresses the filament mesh into the obstructing material.
The present invention is generally directed to an improved balloon catheter for enlarging a flow passage within a vascular conduit or other body passageway. The improved balloon catheter includes a catheter tube which has a longitudinal axis which extends between a proximal end and a distal end. An elongate inner member may be disposed coaxially within the catheter tube. Preferably, this inner member is longitudinally slidable within the catheter tube and configured such that a longitudinal passageway is created between the inner member and the catheter tube for passage of a fluid.
An inflatable and deflatable balloon is disposed coaxially about a distal end of the inner member. The balloon includes a proximal balloon end which is connected to the distal end of the catheter tube and a distal balloon end which is connected to the distal end of the inner member to define an annular balloon chamber or cavity. The annular balloon chamber is fluidly connected with the longitudinal passageway. The balloon is preferably a conventional catheter balloon which is distensible and includes properties for inflating and deflating in response to a fluid passed through the longitudinal passageway.
Alternatively, the balloon ends may only be connected to the inner member. In this configuration, the proximal balloon end is connected to the inner member and the distal balloon end is connected to the distal end of the inner member, distally from the proximal balloon end, to define the annular balloon chamber. A longitudinal passageway extends axially through the inner member and is fluidly connected through an opening within the annular balloon chamber. As previously discussed, the balloon is preferably a conventional catheter balloon and includes properties for inflating and deflating in response to a fluid passed through the longitudinal passageway in the inner member.
An independent outer sleeve is coupled to the catheter and generally surrounds the balloon. The outer sleeve includes a proximal sleeve end which is connected to the distal end of the catheter tube and a distal sleeve end which is connected adjacent the distal end of the inner member distally from the distal balloon end. The outer sleeve is radially expandable into at least one predetermined configuration and size and also collapsible to a minimum radial diameter through longitudinal movement of the inner member relative to the catheter tube. Preferably, the outer sleeve comprises a tubular mesh of a woven or braided filament. The mesh sleeve is configured with varying radial and longitudinal pitches of weave such that unique configurations of the radially expanded mesh are formed when the inner member is moved relative to the outer member. In particular, the outer sleeve may be provided with a reduced radius portion made from a more tightly woven mesh. When expanded, the outer sleeve is xe2x80x9cnecked downxe2x80x9d adjacent this reduced radius portion.
An actuating mechanism is coupled to the catheter tube and the inner tubular member so that they may be moved relative to each other. More particularly, actuation of the actuating member moves the inner member longitudinally relative to the catheter tube such that the outer sleeve is radially expanded into its predetermined configuration. This movement may expand the outer sleeve until it compresses against the inner walls of the vascular conduit or other body passageway. The actuating mechanism is preferably provided with a plurality of incremental or intermediate fixed positions which allow movement of the outer sleeve between a fully collapsed configuration to a fully expanded configuration. This allows opening of a flow passage within a vascular conduit through a continuous and incremental process. This configuration also allows use of a single balloon catheter within a variety of differing conduits.
In another aspect of the present invention, the proximal balloon end is connected to the inner tubular member proximally of the proximal sleeve end and the distal balloon end is connected to the inner tubular member distally of the distal sleeve end. The outer sleeve is not directly connected to the catheter but is centered over the balloon such that, when the balloon is inflated, a pair of annular balloon cavities (expanded balloon sections) are created on either side of the outer sleeve. The outer sleeve may be constructed of a tightly knit weave of filaments such that it is compressively retained on the balloon when the balloon is deflated as well as inflated. Since the expanded balloon sections are unrestrained by the outer sleeve, they may be inflated to a radial diameter much greater than that of the expanded outer sleeve.
A longitudinal passageway is provided through the inner tubular member and fluidly connected to an opening adjacent the outer sleeve. This passageway is used for dispensing a fluid capable of causing the dissolution of dissolving of the affected cells between the spaced apart and expanded balloon sections. The fluid may be a lysin. Alternatively, a vacuum may be drawn through the opening and passageway for the removal of obstructing material or previously applied fluid.
In another embodiment of the present invention, a surgical device for cleaning and removing occlusions from an artificial graft includes a catheter having a longitudinal axis extending between a proximal end and a distal end. An inflatable balloon, coaxial with the catheter, is coupled to the catheter adjacent a distal end. A tubular sleeve having a sleeve proximal end and a sleeve distal end surrounds the balloon. The sleeve is radially expandable and collapsible with the balloon and includes an irregular outer surface for contacting the graft. One end of the tubular sleeve is connected to the catheter to prevent its removal from the balloon.
The catheter further includes a longitudinal passageway having a distal opening for passage of a fluid into and out of the balloon. In addition, a second longitudinal passageway is provided within the catheter and includes an outlet or opening adjacent the balloon for dispensing a lysing agent into the vascular conduit.
A preferred method for enlarging a flow passage within a vascular conduit or other body passageway according to the principles of the present invention, comprises the steps of providing a balloon catheter which includes an inflatable balloon adjacent a distal end and a radially expandable and collapsible outer mesh sleeve which surrounds the balloon. The outer mesh sleeve is configured with an irregular outer surface for contacting the vascular conduit when it is radially expanded. The balloon catheter is then inserted within the vascular conduit. The balloon is then inflated such that the outer mesh sleeve contacts the inner walls of the vascular conduit. This expansion compresses the outer mesh sleeve against the inner walls of the vascular conduit. The balloon is then deflated and the balloon catheter removed from the vascular conduit.
In another aspect of the present invention, the method includes the step of radially expanding the mesh sleeve into a fixed configuration prior to the step of inflating the balloon. In this way, the balloon, when inflated, is restricted to the fixed configuration of the mesh sleeve. This prevents the balloon from overinflating and rupturing or otherwise damaging the vascular conduit. In addition, the fixed configuration may be a unique shape for particular use in enlarging the flow passage or alternatively for therapeutic treatment.
In yet another aspect of the present invention, the method includes the step of moving the balloon catheter within the vascular conduit or other body passageway. This step may be performed after the balloon is inflated such that the mesh sleeve is expanded against the inner walls of the vascular conduit and then rotated or moved longitudinally. This step moves the outer mesh sleeve, which may have an irregular outer surface, against the inner walls of the vascular conduit and enlarges the flow passage.